The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Cooling fan assemblies may provide airflow to dissipate heat generated by electronic components. Cooling fan assemblies may include a motor that drives fan blades. Traditional cooling fan assemblies include a printed circuit board (PCB) mounted inside a housing of the motor. Fan control modules and Hall-effect sensors are mounted on the PCB and used to control a speed of the motor.
Referring now to FIG. 1, a cooling fan system 100 is shown and includes a PCB 101 that is mounted in a motor housing 102. A motor control module 104 is mounted on the PCB 101. Wires 105 connect the PCB 101 to a host device (not shown) via terminals 106 on the PCB 101. An example of a host device is a personal computer.
The motor housing 102 includes a motor 107. The motor 107 may include a two-phase brushless direct current (DC) motor. The motor 107 may include four stator poles: pole A1 108, pole A2 109, pole B1 110, and pole B2 112. Each of the stator poles A1 108, A2 109, B1 110, B2 112 may be wound with stator coils 114. The pole A1 108 and the pole A2 109 may collectively be called “pole pair A”. The pole B1 110 and the pole B2 112 may collectively be called “pole pair B”.
The motor control module 104 may apply a voltage and/or current to the stator coils 114 of the pole pair A to generate a magnetic field between the pole A1 108 and the pole A2 109. Applying the voltage and/or current to the stator coils 114 of the pole pair A may be called “driving phase A”. The motor control module 104 may provide the voltage and/or current to the stator coils 114 of the pole pair B to generate a magnetic field between the pole B1 110 and the pole B2 112. Applying the voltage and/or current to the stator coils 114 of the pole pair B may be called “driving phase B”.
The motor 107 also includes a rotor 116. The rotor 116 may include at least one permanent magnet. The motor control module 104 may drive phase A and/or phase B to actuate the rotor 116 about an axle 118. The axle 118 may mechanically couple the rotor 116 to the motor housing 102. The motor housing 102 includes externally attached fan blades 119. The fan blades 119 are collectively referred to as a fan 120. While the rotor 116 in FIG. 1 rotates between the stator poles A1 108, A2 109, B1 110, B2 112 the motor 107 may alternatively include a rotor that surrounds the stator poles A1 108, A2 109, B1 110, B2 112.
The motor control module 104 may alternate between driving phase A and driving phase B to actuate the rotor 116. At least one Hall-effect sensor 122 may be mounted on the PCB 101 and be used to determine a position and/or a speed of the rotor 116. For example, the Hall-effect sensor 122 may generate a pulse when a magnetic pole of the rotor 116 passes the Hall-effect sensor 122. The motor control module 104 may determine whether the rotor 116 is rotating and/or a speed of the rotor 116 based on the pulses generated by the Hall-effect sensor 122.